I have a custom web part that executes a SharePoint search query and displays the results. I'd like to add controls to the web part so that users can select a date range (ie. start date and end date) to filter the results by. I'd like it to be the kind of control where it looks like an ordinary textbox and when you click it a little calendar pops up for the user to select a date.

What kind of date picker controls are easily available for me to use? I'm hoping there is something that doesn't require a download or install. Something in the SharePoint object model I could use?